Problem: $5fg + fh - f - 9 = 6g - 3$ Solve for $f$.
Combine constant terms on the right. $5fg + fh - f - {9} = 6g - {3}$ $5fg + fh - f = 6g + {6}$ Notice that all the terms on the left-hand side of the equation have $f$ in them. $5{f}g + 1{f}h - 1{f} = 6g + 6$ Factor out the $f$ ${f} \cdot \left( 5g + h - 1 \right) = 6g + 6$ Isolate the $f$ $f \cdot \left( {5g + h - 1} \right) = 6g + 6$ $f = \dfrac{ 6g + 6 }{ {5g + h - 1} }$